One or more embodiments relate to a nonvolatile memory device for storing data and a method of programming the same.
Recently, there has been an increasing demand for nonvolatile memory devices, which can be electrically programmed and erased and do not require the refresh function of rewriting data at specific intervals.
The nonvolatile memory cell is configured to enable electrical program and erase operations and perform the program and erase operations through the use of threshold voltages, which vary when electrons are moved by applying a strong electric field to a thin oxide layer.
The nonvolatile memory device typically includes a memory cell array in which cells for storing data are arranged in a matrix form and a page buffer for writing data into specific cells of the memory cell array or reading data stored in a specific cell. The page buffer includes a bit line pair coupled to specific memory cells, a register for temporarily storing data to be written into the memory cell array or reading data stored in a specific memory cell of the memory cell array and temporarily storing the read data, a sense node for sensing the voltage level of a specific bit line or a specific register, and a bit line selection unit for controlling whether or not to couple the specific bit line to the sensing node.
In a method of programming the nonvolatile memory device, various types of interference phenomena are generated according to a shift in the threshold voltages of neighboring cells. In particular, in a multi-level cell (MLC) program method of storing data of two bits or more in a single cell, a malfunction resulting from the interference phenomena can occur because a margin between threshold voltages of each state becomes narrow. Accordingly, there is a need to minimize the interference phenomena resulting from the program operations of neighboring cells.